(19)
(11) EP 0 403 121 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
08.05.1991 Bulletin 1991/19

(43) Date of publication A2:
19.12.1990 Bulletin 1990/51

(21) Application number: 90305969.9

(22) Date of filing: 31.05.1990
(51) International Patent Classification (IPC)5: G06T 13/00
(84) Designated Contracting States:
DE FR GB

(30) Priority: 16.06.1989 US 367284

(71) Applicant: International Business Machines Corporation
Armonk, N.Y. 10504 (US)

(72) Inventors:
  • Beitel, Bradley James
    Woodside, CA 94062 (US)
  • Gordon, Robert Douglas
    Sunnyvale, CA 94087 (US)

(74) Representative: Burt, Roger James, Dr. et al
IBM United Kingdom Limited Intellectual Property Department Hursley Park
Winchester Hampshire SO21 2JN
Winchester Hampshire SO21 2JN (GB)


(56) References cited: : 
   
       


    (54) Computer controlled screen animation


    (57) Method and apparatus for generating relative movement between a first image and a second image while avoiding display screen flicker is disclosed. The method includes a step of copying to a first buffer a portion of a display memory corresponding to a present portion of the second image wherein a first image will first appear. The method further includes the steps of superposing within the display memory the first image upon the present portion of the second image and copying to a second buffer the portion of the display memory corresponding to the present portion of the second image, including the first image superposed thereon, and a portion of the display memory corresponding to a next portion of the second image wherein the first image will next appear. The method further includes the steps of erasing the first image from the second buffer by copying the present portion from the first buffer to the second buffer and superposing, within the second buffer, the first image upon the next portion of the second image. The method includes a further step of copying the second buffer to the display memory such that the first image disappears from the present portion of the second image while simultaneously appearing within the next portion of the second image, thereby avoiding display screen flicker.







    Search report